US4700067A - Apparatus for checking atmospheric pollution due to alpha particle emitting aerosols - Google Patents
Apparatus for checking atmospheric pollution due to alpha particle emitting aerosols Download PDFInfo
- Publication number
- US4700067A US4700067A US06/727,450 US72745085A US4700067A US 4700067 A US4700067 A US 4700067A US 72745085 A US72745085 A US 72745085A US 4700067 A US4700067 A US 4700067A
- Authority
- US
- United States
- Prior art keywords
- filter
- detector
- aerosols
- grid
- planar face
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T7/00—Details of radiation-measuring instruments
- G01T7/02—Collecting means for receiving or storing samples to be investigated and possibly directly transporting the samples to the measuring arrangement; particularly for investigating radioactive fluids
- G01T7/04—Collecting means for receiving or storing samples to be investigated and possibly directly transporting the samples to the measuring arrangement; particularly for investigating radioactive fluids by filtration
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S250/00—Radiant energy
- Y10S250/02—Radon detection
Definitions
- the present invention relates to an apparatus for checking atmospheric pollution, which is more particularly applicable to atmospheres polluted by alpha particle emitting aerosols.
- the invention is more particularly applicable to the case where the aerosols contain plutonium, uranium, curium or other elements, whereof the energies of the alpha particles are generally below 6 MeV.
- the decay products of radon isotopes contained in the atmosphere and which are themselves alpha particle emitters are highly prejudicial to the measurements, particularly radium A (Po-218) and thorium C (Bi-212), which have an emission energy of 6 MeV, radium C' (Po-214) having an emission energy of 7.7 MeV and thorium C' (Po-212) having an emission energy of 8.8 MeV.
- the conventional method used for detecting these aerosols consists of sucking air through a filter, which stops the aerosol.
- This filter is placed in front of a spectrometric detector associated with amplitude selectors making it possible to discriminate the emissions due to the radon from those due to the aerosols in question.
- the often circular detector is positioned parallel to the filter and facing the same, on the side where the aerosols are trapped and at a distance of a few millimeters. This space is necessary to permit the passage of the gaseous stream carrying the aerosols.
- the energy of the alpha particles emerging from the filter towards the detector is partly absorbed by the air. Certain particles follow a path which is perpendicular to the filter and detector, whilst others follow a more or less sloping path.
- the alpha particles are detected with an energy which becomes smaller the longer the path which they have followed in the air, i.e. the more it is inclined with respect to the direction perpendicular to the filter and the detector.
- This energy loss leads to a superimposing of the "degraded" energies of the alpha particles of the decay products of the radon isotopes and the lower energies of the alpha particles of the isotopes which it is wished to detect.
- FIG. 1 is a graph giving the number N of alpha particles detected as a function of the emission energy E.
- This graph shows two peaks, one of which corresponds to the alpha particles of the radium C', whilst the other corresponds to the alpha particles of the radium A and thorium C.
- Those particles have undergone an energy loss by interaction with air. Their remaining degraded energy is of the same order of magnitude as that of the alpha particles of e.g. plutonium 238 and is superimposed on the energy peak of the latter.
- the hatched area A to the left of the peak corresponding to the radium A and thorium C corresponds to spurious pulses due to the radon in the window useful for detecting plutonium 238.
- the first consists of arranging a grid with closed cells between the filter and the detector for stopping the alpha particles which do not follow a direction quasi-perpendicular to the latter.
- FIG. 2 where it can be seen that it comprises a filter 2 shaped like a flat disk and a detector 4 having a circular shape and having a planar detection face 6 facing filter 2.
- a grid 8' Between filter 2 and face 6 of detector 4 is arranged a grid 8' having a certain number of cells 10.
- the grid whose periphery is closed by plates perpendicular to the filter and detector, each cell being open, on the one hand, on the side of the filter and, on the other, on the side of the detector.
- the cells have a square cross-section, the side length being approximately 1 mm, whilst the total grid thickness is generally a few millimeters.
- this apparatus stops the alpha particles following an inclined path with respect to the direction perpendicular to the filter and detector, it suffers from the disadvantage that in order to permit the passage of the gaseous stream carrying the alpha particles, it is necessary to provide a space between the filter and the grid. This leads to a by no means negligible spacing between the filter and detector, which causes a supplementary energy loss of alpha particles of aerosols trapped on the filter and which it is wished to detect.
- Another method consists of using algorithms for evaluating the number of spurious alpha particles and they are eliminated by removal from the recorded spectrum.
- this method leads to imprecise results.
- the object of the present invention is to eliminate these disadvantages by proposing an apparatus for checking contamination making it possible to directly measure the energy of the alpha particles of the aerosols without any significant loss in the detection efficiency and without requiring supplementary calculations.
- pollution checking apparatus has a flat filter which holds back the aerosols, a detector having a planar detection face facing the filter and parallel thereto and a grid positioned between the filter and said planar face of the detector.
- the grid comprises a plurality of plates arranged both radially and perpendicularly to the filter and to said planar detector face. Each plate extends over the entire distance between the filter and the planar face and the plates define between them cells, each of which is open towards the outside of the space between the filter and the detector.
- the filter and the planar face of the detector are circular, thus defining a cylindrical space.
- the plates constituting the grid pass through the axis of said cylindrical space and form sectors which are open towards the outside.
- the filter and detector are circular, other shapes are possible (e.g. polygonal).
- the apparatus must have an axis of symmetry perpendicular to the filter and detector, in order that the air flow is regularly distributed around the entire apparatus.
- the plates extend in a direction containing the axis of symmetry, i.e. in a radial direction, even if the shape of the apparatus is not circular. It is in this sense that it is necessary to understand the expression "arranged radially" used in the present text.
- this arrangement means that the air can penetrate up to the center of the apparatus and the aerosols are regularly distributed over the entire surface of the filter.
- FIG. 1 a graph indicating the number of alpha particles detected as a function of the emission energy.
- FIG. 2 already described, a diagrammatic perspective view of a prior art checking apparatus.
- FIG. 3 a diagrammatic perspective view of an apparatus according to the invention.
- FIG. 4 a diagrammatic view in elevation and partly in section illustrating a possible arrangement of the apparatus according to the invention.
- FIG. 3 illustrates an apparatus according to the invention which comprises, in conventional manner, a filter 2 facing a planar face 6 of a detector 4, the latter being connected to measuring means by a group of electrical wires 12.
- a grid 8 is arranged between filter 2 and detector 4.
- filter 2 and detector 4 are circular.
- Grid 8 comprises six plates 14 arranged both perpendicularly to filter 2 and detector face 6 and radially relative to the axis of symmetry of the cylinder defined by the filter and the detector face 6. In this case, there are six plates forming between them an angle of 60°, but it would not pass beyond the scope of the invention to modify the number of plates. It can be seen that two adjacent plates define between them a cell or cavity shaped like a sector 16, which is open on the outside of the cylinder defined by filter 2 and detector 4.
- r designates the radius of the filter and the detector
- d designates the distance between filter 2 and the face 6 of detector 4.
- E 1 is the energy of the spurious elements
- E 0 is the energy of the sought pollutant
- the optimization consists of seeking value d and r pairs satisfying equation (3).
- FIG. 4 illustrates a possible arrangement of the apparatus according to the invention for carrying out direct atmospheric sampling (sampling at a more remote point would require a much more complex arrangement).
- the apparatus of FIG. 4 comprises a tube 18 used for sucking in the atmosphere to be checked, the upper part 18a of the tube 18 being widened.
- a support part 20 is mounted on portion 18a of tube 18 by means of lugs 22.
- Part 20 is also fixed to a table or another support 24 diagrammatically represented in mixed lines in FIG. 4.
- the portion 18a of tube 18 also supports a filter holder 26, which supports the filter 2.
- Grid 8 identical to that illustrated in FIG. 3, forms the mechanical connection between support 20 and detector 4 within box 28, the latter also containing all the electronics associated with the detector 4.
- Filter holder 26 comprises a circular portion 27 supporting a fritted or perforated central disk 29 allowing the passage of the air flow, while retaining the actual filter 2.
- the apparatus according to the invention has numerous advantages, because it enables detection of alpha particle emitting aerosols by a direct measurement and without the measurement being disturbed by spurious energies due to radon derivatives.
- the apparatus can easily be realised and can be combined with a simple device, like that of FIG. 4, which reduces the manufacturing costs thereof.
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- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Molecular Biology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Measurement Of Radiation (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
Description
P.sub.max =(r.sup.2 +d.sup.2).sup.1/2 (1)
P.sub.(cm) =0.32×E.sup.3/2 (MeV) (at atmospheric pressure) (2)
(r.sup.2 +d.sup.2).sup.1/2 -d=0.32×(E.sub.1.sup.3/2 -E.sub.0.sup.3/2) (3)
TABLE 1 ______________________________________ Useful surface S in mm.sup.2 of d in mm r in mm detector and filter ______________________________________ 3 8.2 211 3.5 8.5 227 4 8.8 243 p = 1 bar 4.5 9.2 265 5 9.5 283 ______________________________________
TABLE 2 ______________________________________ d in mm r in mm Useful surface S in mm.sup.2 ______________________________________ 3 10.8 369 3.5 11.2 395 4 11.6 420 p = 0.7 bar 4.5 11.9 447 5 12.3 473 ______________________________________
Claims (2)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8406690A FR2563633B1 (en) | 1984-04-27 | 1984-04-27 | DEVICE FOR CONTROLLING ATMOSPHERIC CONTAMINATION DUE TO ALPHA PARTICLE EMITTING AEROSOLS |
FR8406690 | 1984-04-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
US4700067A true US4700067A (en) | 1987-10-13 |
Family
ID=9303572
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/727,450 Expired - Lifetime US4700067A (en) | 1984-04-27 | 1985-04-26 | Apparatus for checking atmospheric pollution due to alpha particle emitting aerosols |
Country Status (4)
Country | Link |
---|---|
US (1) | US4700067A (en) |
EP (1) | EP0162751B1 (en) |
DE (1) | DE3566460D1 (en) |
FR (1) | FR2563633B1 (en) |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4820925A (en) * | 1987-03-23 | 1989-04-11 | The United States Of America As Represented By The United States Department Of Energy | Room air monitor for radioactive aerosols |
WO1989004499A1 (en) * | 1987-11-05 | 1989-05-18 | Gjerdrum David M | Device for monitoring radon exposure |
US4861985A (en) * | 1986-04-08 | 1989-08-29 | Pai Hsiang L | Time-averaged radon daughters (WL) dosimeter and method for surveys of indoor, outdoor and underground (MINE) contamination |
US4864143A (en) * | 1986-04-08 | 1989-09-05 | Pai Hsiang L | Time-average radon daughters (WL) dosimeter for mines, indoor and environment survey |
US4880973A (en) * | 1988-07-15 | 1989-11-14 | Reynolds John D | Ground radon flux sampling device |
US4888485A (en) * | 1988-06-27 | 1989-12-19 | The United States Department Of Energy | Beta/alpha continuous air monitor |
US4897549A (en) * | 1988-12-19 | 1990-01-30 | Zerda Tadeusz W | Method of measuring pore diameters by positronium decay |
US4975574A (en) * | 1990-01-05 | 1990-12-04 | Henry Lucas | Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture |
US4990786A (en) * | 1987-10-09 | 1991-02-05 | Fag Kugelfischer Georg Schafer (Kgaa) | Method and apparatus for determining the actual artificial aerosol alpha activity concentration in the air |
US5087820A (en) * | 1989-05-31 | 1992-02-11 | Digital Diagnostic Corp. | Radiometric analysis system for solid support samples |
AU624349B2 (en) * | 1987-11-05 | 1992-06-11 | David M. Gjerdrum | Device for monitoring radon exposure |
US5128539A (en) * | 1990-08-15 | 1992-07-07 | The United States Of America As Represented By The United States Department Of Energy | Apparatus having reduced background for measuring radiation activity in aerosol particles |
US5204528A (en) * | 1989-06-09 | 1993-04-20 | Consultec Scientific, Inc. | System for determining health risk due to radon progeny and uses thereof |
US5635403A (en) * | 1991-12-13 | 1997-06-03 | Nuclear Fuel Services, Inc. | Sample containment card for air or station contamination monitoring system and process |
US20030175982A1 (en) * | 2002-02-06 | 2003-09-18 | Gerald Smith | Positron annihilation monitor and method for detecting hazardous materials |
WO2005086605A2 (en) * | 2004-03-17 | 2005-09-22 | Young-Woong Park | An alpha track detector with foldable semicircle ring |
US10031060B2 (en) | 2016-07-13 | 2018-07-24 | Mauro & Associates, Llc | Continuous, real time monitor for airborne depleted uranium particles in the respiratory range and corresponding method of use |
WO2022152909A1 (en) * | 2021-01-18 | 2022-07-21 | Radonova Laboratories Ab | Device and method for determining radon concentration |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR3111714B1 (en) | 2020-06-22 | 2022-10-28 | Commissariat Energie Atomique | System for correlating alpha and gamma spectrometry measurements for in situ radiological characterization of a sample |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2497823A (en) * | 1946-06-10 | 1950-02-14 | Everett W Molloy | Radiation measuring device for air filters |
US3922555A (en) * | 1972-07-13 | 1975-11-25 | Commissariat Energie Atomique | Portable instrument for selectively detecting alpha-particles derived from radon |
US4185199A (en) * | 1978-06-29 | 1980-01-22 | The United States Of America As Represented By The Secretary Of The Interior | Method of continuously determining radiation working level exposure |
US4186303A (en) * | 1978-01-12 | 1980-01-29 | Westinghouse Electric Corp. | Exclusion of alpha particles from thoron in uranium detection |
US4253025A (en) * | 1978-09-14 | 1981-02-24 | The United States Of America As Represented By The Department Of Energy | Hand and shoe monitor using air ionization probes |
US4385236A (en) * | 1979-06-30 | 1983-05-24 | Kernforschungszentrum Karlsruhe | Passive dosimeter for detection of radon, thoron and daughters thereof |
US4442358A (en) * | 1979-11-23 | 1984-04-10 | Munchener Apparatebau Fur Elektronische Gerate Kimmel Gmbh | Apparatus for detecting α-rays present in a specified energy range |
-
1984
- 1984-04-27 FR FR8406690A patent/FR2563633B1/en not_active Expired
-
1985
- 1985-04-22 EP EP85400790A patent/EP0162751B1/en not_active Expired
- 1985-04-22 DE DE8585400790T patent/DE3566460D1/en not_active Expired
- 1985-04-26 US US06/727,450 patent/US4700067A/en not_active Expired - Lifetime
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2497823A (en) * | 1946-06-10 | 1950-02-14 | Everett W Molloy | Radiation measuring device for air filters |
US3922555A (en) * | 1972-07-13 | 1975-11-25 | Commissariat Energie Atomique | Portable instrument for selectively detecting alpha-particles derived from radon |
US4186303A (en) * | 1978-01-12 | 1980-01-29 | Westinghouse Electric Corp. | Exclusion of alpha particles from thoron in uranium detection |
US4185199A (en) * | 1978-06-29 | 1980-01-22 | The United States Of America As Represented By The Secretary Of The Interior | Method of continuously determining radiation working level exposure |
US4253025A (en) * | 1978-09-14 | 1981-02-24 | The United States Of America As Represented By The Department Of Energy | Hand and shoe monitor using air ionization probes |
US4385236A (en) * | 1979-06-30 | 1983-05-24 | Kernforschungszentrum Karlsruhe | Passive dosimeter for detection of radon, thoron and daughters thereof |
US4442358A (en) * | 1979-11-23 | 1984-04-10 | Munchener Apparatebau Fur Elektronische Gerate Kimmel Gmbh | Apparatus for detecting α-rays present in a specified energy range |
Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4861985A (en) * | 1986-04-08 | 1989-08-29 | Pai Hsiang L | Time-averaged radon daughters (WL) dosimeter and method for surveys of indoor, outdoor and underground (MINE) contamination |
US4864143A (en) * | 1986-04-08 | 1989-09-05 | Pai Hsiang L | Time-average radon daughters (WL) dosimeter for mines, indoor and environment survey |
US4820925A (en) * | 1987-03-23 | 1989-04-11 | The United States Of America As Represented By The United States Department Of Energy | Room air monitor for radioactive aerosols |
US4990786A (en) * | 1987-10-09 | 1991-02-05 | Fag Kugelfischer Georg Schafer (Kgaa) | Method and apparatus for determining the actual artificial aerosol alpha activity concentration in the air |
WO1989004499A1 (en) * | 1987-11-05 | 1989-05-18 | Gjerdrum David M | Device for monitoring radon exposure |
US4891514A (en) * | 1987-11-05 | 1990-01-02 | David M. Gjerdrum | Device for monitoring radon exposure |
AU624349B2 (en) * | 1987-11-05 | 1992-06-11 | David M. Gjerdrum | Device for monitoring radon exposure |
US4888485A (en) * | 1988-06-27 | 1989-12-19 | The United States Department Of Energy | Beta/alpha continuous air monitor |
US4880973A (en) * | 1988-07-15 | 1989-11-14 | Reynolds John D | Ground radon flux sampling device |
US4897549A (en) * | 1988-12-19 | 1990-01-30 | Zerda Tadeusz W | Method of measuring pore diameters by positronium decay |
US5087820A (en) * | 1989-05-31 | 1992-02-11 | Digital Diagnostic Corp. | Radiometric analysis system for solid support samples |
US5204528A (en) * | 1989-06-09 | 1993-04-20 | Consultec Scientific, Inc. | System for determining health risk due to radon progeny and uses thereof |
US4975574A (en) * | 1990-01-05 | 1990-12-04 | Henry Lucas | Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture |
US5128539A (en) * | 1990-08-15 | 1992-07-07 | The United States Of America As Represented By The United States Department Of Energy | Apparatus having reduced background for measuring radiation activity in aerosol particles |
US5635403A (en) * | 1991-12-13 | 1997-06-03 | Nuclear Fuel Services, Inc. | Sample containment card for air or station contamination monitoring system and process |
US20030175982A1 (en) * | 2002-02-06 | 2003-09-18 | Gerald Smith | Positron annihilation monitor and method for detecting hazardous materials |
US7041508B2 (en) | 2002-02-06 | 2006-05-09 | Alerttechsystems, Llc | Positron annihilation monitor and method for detecting hazardous materials |
WO2005086605A2 (en) * | 2004-03-17 | 2005-09-22 | Young-Woong Park | An alpha track detector with foldable semicircle ring |
WO2005086605A3 (en) * | 2004-03-17 | 2005-11-17 | Young-Woong Park | An alpha track detector with foldable semicircle ring |
US20070194221A1 (en) * | 2004-03-17 | 2007-08-23 | Young-Woong Park | Alpha track detector with foldable semicircle ring |
US10031060B2 (en) | 2016-07-13 | 2018-07-24 | Mauro & Associates, Llc | Continuous, real time monitor for airborne depleted uranium particles in the respiratory range and corresponding method of use |
WO2022152909A1 (en) * | 2021-01-18 | 2022-07-21 | Radonova Laboratories Ab | Device and method for determining radon concentration |
Also Published As
Publication number | Publication date |
---|---|
FR2563633B1 (en) | 1986-07-18 |
EP0162751B1 (en) | 1988-11-23 |
FR2563633A1 (en) | 1985-10-31 |
DE3566460D1 (en) | 1988-12-29 |
EP0162751A1 (en) | 1985-11-27 |
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